Class LruMemoryStore.SpoolingLinkedHashMap

  extended by java.util.AbstractMap<K,V>
      extended by java.util.HashMap<K,V>
          extended by java.util.LinkedHashMap
              extended by
All Implemented Interfaces:
Serializable, Cloneable, Map
Enclosing class:

public final class LruMemoryStore.SpoolingLinkedHashMap
extends LinkedHashMap

An extension of LinkedHashMap which overrides removeEldestEntry(java.util.Map.Entry) to persist cache entries to the auxiliary cache before they are removed.

This implementation also provides LRU by access order.

See Also:
Serialized Form

Nested Class Summary
Nested classes/interfaces inherited from class java.util.AbstractMap
AbstractMap.SimpleEntry<K,V>, AbstractMap.SimpleImmutableEntry<K,V>
Constructor Summary
          Default constructor.
Method Summary
 Object put(Object key, Object value)
protected  boolean removeEldestEntry(Map.Entry eldest)
          Returns true if this map should remove its eldest entry.
Methods inherited from class java.util.LinkedHashMap
clear, containsValue, get
Methods inherited from class java.util.HashMap
clone, containsKey, entrySet, isEmpty, keySet, putAll, remove, size, values
Methods inherited from class java.util.AbstractMap
equals, hashCode, toString
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.Map
containsKey, entrySet, equals, hashCode, isEmpty, keySet, putAll, remove, size, values

Constructor Detail


public LruMemoryStore.SpoolingLinkedHashMap()
Default constructor. Will create an initial capacity of 100, a loading of .75 and LRU by access order.

Method Detail


protected final boolean removeEldestEntry(Map.Entry eldest)
Returns true if this map should remove its eldest entry. This method is invoked by put and putAll after inserting a new entry into the map. It provides the implementer with the opportunity to remove the eldest entry each time a new one is added. This is useful if the map represents a cache: it allows the map to reduce memory consumption by deleting stale entries.

Will return true if:

  1. the element has expired
  2. the cache size is greater than the in-memory actual. In this case we spool to disk before returning.

removeEldestEntry in class LinkedHashMap
eldest - The least recently inserted entry in the map, or if this is an access-ordered map, the least recently accessed entry. This is the entry that will be removed it this method returns true. If the map was empty prior to the put or putAll invocation resulting in this invocation, this will be the entry that was just inserted; in other words, if the map contains a single entry, the eldest entry is also the newest.
true if the eldest entry should be removed from the map; false if it should be retained.


public Object put(Object key,
                  Object value)

Specified by:
put in interface Map
put in class HashMap


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